[Study on atmospheric particles and their long-term trend in Beijing cleaning area].

Observational data in clean area provides important references for evaluating environmental impact both from natural and anthropogenic sources. Atmospheric particulate matter of different size were closely examined using dustfall data during 1980-2009, TSP data during 1991-2009 and PM10 data since 2000 at Dingling station (DL), which was located in the clean area of Beijing. It was shown that dustfall amount at DL was on decrease in the last 30 years, by reasons of anthropogenic emission control and ecological environment improvement; meanwhile there was a 5-6 years' cycle of variation in yearly dustfall amount partly caused by dust storms. Similarly TSP and PM10 concentrations changed greatly but had a decreasing trend since 2000. Furthermore, the ratios of Pb and BaP in TSP at DL, namely Pb/TSP and BaP/TSP, were analyzed for anthropogenic influence. It was proved that the ratios were increasing and there was stronger influence of regional pollutant transport from urban areas. Lastly, it was also found that the coarser atmospheric particles were, the stronger their seasonal fluctuations in mass were, which were mainly affected by local sources rather than regional, and vice verse.